A crucial step in the manufacturing of integrated circuits is the testing of those circuits after device fabrication. As with each of the steps involved in integrated circuit manufacture, it is advantageous to perform this testing with as little cost as possible. Therefore, high speed, automated integrated circuit testers are necessary.
As integrated circuits become more complex and require more pins for interconnection to circuit boards and the like, the apparatus necessary for testing the integrated circuits becomes much more complex. Early integrated circuit testers used a single force and measure unit which was serially connected to each of the pins to be tested. The force and measure unit applies predetermined forcing conditions of voltage and/or current to the pin and measures the response thereto. More recent automated testers have moved in the direction of multiple force and measure units and have reached the point of dedication of a single force and measure unit to each pin to be tested. Typically, a minicomputer contains the testing and measuring routines and is responsible for managing the testing process.
The speed of the current generation of automated integrated circuit testers is limited by the speed at which the management computer can communicate with all of the force and measure units and associated electronics. Since the amount of information which must be passed from the management computer to the test electronics to specify a given test state and measurement criteria is so large, the communication speed is relatively slow.